Check valves are well-known and widely used in fluid systems of various types to permit fluid flow in one direction therethrough while preventing fluid flow in the opposite direction. Such check valves have a variety of different forms, principally ball check valves in which a spherical ball is held by a spring adjacent a seat until opened by fluid pressure overcoming the spring bias, flapper valves in which a generally flat valve member is pivoted between open and closed positions, and check valves having generally conical valve members operating in a similar manner as the aforesaid ball check valve.
These known types of check valves are generally satisfactory in terms of carrying out this intended function of permitting one-way flow through a fluid line, but they frequently have undesirable side effects. For example, it is desirable for the valve member to be somewhat loosely held in its movable mounting arrangement so that it can adjust to some extent for accommodating slight misalignment with its seat, but loosely held valves will usually suffer the disadvantage of excessive vibration resulting from the forces of the fluid acting thereagainst when the valve member is at its open position. Antithetically, if the valve member is tightly held during its opening and closing movement to prevent excessive vibration, it will often not seat properly on the valve seat when it closes, thereby resulting in undesirable leakage past the valve member. Additionally, conventionally check valves generally have high pressure losses thereacross, particularly where the fluid flowing therethrough must alter direction significantly, as in most flapper valves, or where the cross-sectional flow area through the valve varies substantially along the longitudinal extent of the valve.
In accordance with the present invention, a check valve is provided which substantially overcomes many of the aforesaid drawbacks of conventional check valves, and which is simple and relatively inexpensive to produce.